Guillermo del Toro pulls an Alfred Hitchcock in The Shape of Water by making a cameo appearance in his own film, but leave it to one of the world’s most imaginative filmmakers to come up with the most imaginable cameo possible. The movie’s supervising sound editor Nathan Robitaille confirms to Vanity Fair that del Toro appears in The Shape of Water as the fish creature’s breath, so you’ll have to listen closely to spot the cameo.

Robitaille worked closely with del Toro to get the sound of the fish just right. Because the fish has to be an object of desire to the main character and is essentially the film’s co-romantic lead, Robitaille’s biggest challenge was finding sounds to represent that. He recorded pigeons cooing, for instance, to layer into the sound during the creator’s more tender moments on screen, like when Elisa fills the bathroom with water.

“This is the first time I’ve been able to give a creature this much range,” Robitaille told Vanity Fair. “We walked away from the first meeting with Guillermo not sure what the creature would sound like [but there was pressure] because he was the romantic lead.”

Ironically, del Toro’s breathing would be a key ingredient in perfecting the creature’s sound. Robitaille noticed the director’s raspy voice and breathing patterns on set and invited the filmmaker into the recording studio to experiment with sounds.

“Once we got [del Toro] into the studio, it was obvious pretty fast that the most beautiful texture was coming from his breathing,” Robitaille said. “So I started harvesting his breaths that I got between takes and glued everything together.”

So yes, you’re actually hearing some of del Toro’s own breathing when the fish creature breathes. Robitaille said del Toro’s breathing is most obvious in the scenes where the feature is gasping for air when he’s out of water.

The Shape of Water is nominated for 13 Academy Awards, including Best Picture. Robitaille is nominated in the Best Sound Editing category.